1. Field of the Invention
The present invention relates to a semiconductor memory apparatus and a fabrication method of the same, and in particular to an anti-fuse for programming a redundancy cell, a repair circuit having a programming apparatus, and a fabrication method of the anti-fuse which are capable of simply implementing a programming operation when exchanging a defective cell of a semiconductor memory apparatus with a redundancy cell.
2. Description of the Conventional Art
Generally, in the semiconductor memory apparatus, a plurality of redundancy cells of a memory are connected by the block formed of sub-arrays. For example, extra rows and columns are connected at every 256K cell array for thereby exchanging a defective memory cell with an extra cell by the unit of row and column. In such a repair circuit, when a wafer fabrication process is completed, the defective cells are removed based on a predetermined test, and an address signal of a corresponding redundancy cell is changed in an internal circuit through a programming operation, so that when an address corresponding to a defective line is inputted during an actual use, the line is exchanged with a line of a corresponding cell. As the programming methods, an electric fuse method which is capable of melting and cutting a fuse using an over-current, a method for burning the fuse using a laser beam, a method for making a junction portion short-circuit using a laser beam, etc. are known. Among these methods, the method for cutting the fuse using a laser beam is simple, and in this method, it is possible to easily implement a desired layout.
However, in the laser-based programming method, a repair process which needs an expensive laser apparatus for exchanging a defective cell with a redundancy cell is used. In addition, a laser beam is radiated onto the fuse by an additional fuse window process for cutting the same, and then the programming and a passivation process are performed, whereby the repair process is complicated.